Chapter 5x: Unbroken Heart is the only side mission found in Fire Emblem: The Sacred Stones and is a mandatory mission which requires nothing to be played. It features Ephraim, prince of Renais and son of King Fado. This is the first mission in which the player is able to use Ephraim and his three knights.

Despite lacking funds, Ephraim charges the stronghold in Grado in hopes of diverting attention to Renais, where he hopes his family remains in power. Ephraim is unaware that Renais has already been overthrown and his father killed. Together, he, Forde, Kyle and Orson, his three very trusted knights, seize the castle.

It is revealed that Zonta, the boss in this chapter, is a pawn in Valter's schemes, acting solely as bait as opposed to a force meant to stop Ephraim. Once seized, Ephraim and company witness reinforcements outside who have been waiting to close the group in. Ephraim is then imprisoned and not freed until later in the story.

Ephraim, prince of Renais and brother to Eirika. This is the first chapter playable by Ephraim and foreshadows his later usage.

Kyle, trusted knight of Ephraim. Kyle will be usable in future chapters as well.

Forde, brother of Franz and trusted knight of Ephraim. Forde will also be usable in future chapters.

Orson, paladin and (foolishly) trusted knight of Ephraim. Orson will defect to Grado's side after this chapter and will no longer be usable. Strategically, Orson should not be allowed to gain any experience, as it will simply go to waste. His items should also all be traded out, as they will disappear if not. This is the only chapter Orson is a playbale character other than when he is unlocked via Creature Campaign.

These units can not die. If killed, they will simply retreat and continue being usable in future chapters.

Ideally, it is wise to immediately trade all of Orson's items to a unit of your choosing, including his Vulnerary. The item is useless to him, as most units will inflict very little-to-no damage. He can then be used as a meat shield when the others are inflicted with damage.

Use the narrow passage ways to your advantage, attacking from afar with Forde's Javelin and killing off the Shaman hastily. Try to separate your men when you reach the narrow passage way, as to avoid being sandwiched by enemy units.

Keeping experience focused on one character is wise. Forde and Kyle, unless you want to use them later on, should be more focused on Ephraim, who will be a vital character in the future chapters. Using Elixirs and Vulneraries should also be monitored.